“For most of history, man has had to fight nature to survive; in this century he is beginning to realize that, in order to survive, he must protect it.”

―Jacques-Yves Cousteau

Following on from last month’s climate talks in Paris, and in the wake of bizarre weather patterns that are currently sweeping the globe, we here at Words in mOcean have decided to begin the year by focusing our attention on climate change and our oceans.

Alien abductions, wormholes, peculiarities in the Earth’s magnetic field, energy crystals from The Lost City of Atlantis ─ these are just a few of the far-fetched theories that have been proposed in order to explain the disappearance of ships and planes in the mysterious Bermuda Triangle. But does the Bermuda Triangle really exist? Or is it just a legend that has grown out of control?

We still do not fully understand where all the water on this planet, including that in the ocean, originally came from. At a fundamental level we know how water in the universe comes into existence: when stars reach the end of their lives in a violent explosion called a super­nova, there is enough heat and pressure to bring oxygen and hydrogen together to form water. When The Solar System was forming, 9 billion years after the big bang, there is no doubt that water would have been an ingredient in the dust cloud that went on to form The Sun and its planets. But scientists think that Earth would have been a lot hotter than it is today; and with no atmosphere any water hanging around would have simply evaporated into space. That means that The Earth must have gained its water sometime after it was formed.

Water is made from oxygen and hydrogen under the enormous heat and pressure created during a supernova, where a star reaches the end of its life and explodes. Image credit: NASA, ESA & G. Bacon / Wikipedia commons.

People often mistakenly think that the sea is blue because it reflects the sky, but the truth is that pure water is very slightly blue. It is just so pale that in small quantities it appears clear.

Water is blue because it absorbs red, yellow and green light, but scatters blue light.

Fundamentally, what makes water blue is the fact that it absorbs light that is red, yellow and green, and scatters light that is blue ─ this is because blue light travels as shorter, smaller waves that are scattered more easily (this is essentially the same reason why the sky is also blue). The reason a small amount of water appears clear is because not much light is scattered. In larger bodies of water there are more water molecules for light to collide with, resulting in more blue light being scattered. Think of it like throwing a bucket-full of tennis balls against a tree from a distance: the chances are that most balls will miss the tree and keep going. But if you stand in a forest and throw tennis balls, more balls will hit trees and bounce back. It is exactly the same when it comes to light hitting water molecules: if there are more water molecules in the way, more light particles will collide with them and be scattered, making the water appear a deeper shade of blue.

Imagine that all of the water in the oceans evaporated, just leaving the salt (sodium chloride) behind. Now imagine that you gathered up all that salt and spread it equally over the Earth’s land surface (perhaps with a little help from a few million other people). How deep do you think that layer of salt would be? One estimate is 500 feet, or just over 150 meters!

If you evenly spread all the salt in the ocean over the surface of the Earth it would completely bury the tallest rollercoaster on the planet! Image credit: Dusso Janladde/ Wikipedia commons.